Conventional overload protecting equipments, mechanisms and/or installments used in a larger plant or industrial fields function to be a protector to detect/interrupt a specific current and/or use a fuse to interrupt a power supply at more than a specific temperature, which are commercially obtainable, but these often caused causalities and a great amount of losses and damages to a society due to a failure of the properly interruption to the power supply.
Substantially, as a current on a power line applied to a motor having a rotational shaft is transited into an instantly peak one, it is known that the electrical line is designed to stand by two times of a maximum acceptable current. But, an electrical accident often occurs at a death zone; adjacent to an input terminal of a relay device that divides a larger current into a smaller current.
A temperature fuse has its own inherent error operational property, which is not widely used in an industrial field. At that case that electrical appliance equipment consumes a maximum current at its normal state, a temperature of an electrical line connected thereto and its surface temperature may be often raised following by influencing a room temperature, so it makes the appliance equipment or mechanism difficult to be accurately controlled. Further, it is difficult to spot the breakage of the temperature fuse, visibly, and to make the maintenance and repair thereof without being monitored.
In other words, interrupters, electrical lines, cables, receptacles, other power appliances, etc. are being deteriorated due to their use environment and condition or a number of factors caused in their electrical circuit, so it often results in an important cause of an electrical accident or causes an electrical accident, directly. Even through the same appliances are used, they may have a little difference according to their use conditions.
General gradual failure factors are as follows:                {circle around (1)} It often happens due to an arc loss followed by an opening/closing of a surge voltage and an overload current that are known as an electrical factor.        {circle around (2)} It often happens due to an overload, breakage, undesirable harmonic wave inflow, heat cycle (Expanding & Extracting, Stress, Distortion, and Elasticity deteriorating that are known as a thermal factor.        {circle around (3)} It often happens due to fatigues, cracks, breakages, abrasion, deformation, poor contact, etc. caused by the repetitive operating, external stress, vibration, impact, over current or short-circuit, etc. which are known as a mechanical factor.        {circle around (4)} It often happens due to the dusts, strains, salts attached, humidity, high temperature, corrosiveness, ultraviolet ray (poor surface insulations), grease hardness (poor operating), metal corrosion (poor contact, breakage), deterioration of an insulating material, etc. that are known as an environmental factor.        {circle around (5)} It often happens due to the insulating deterioration, partly discharging phenomena (corrosion accelerated by a chemical forming material followed by a corona phenomena), etc. that are known as a chemical factor.        
In the progress of the deterioration due to these factors as described above, interrupters, electrical lines, cables, adapters or receptacle, other power equipments and mechanisms, etc. increase the resistance to a temperature resulted from its temperature coefficient, whereby an amount of current that is generated by their overload operating is reduced, it blocks the operating of their interrupter, thereby causing a fire.
In cases that the deterioration happens due to such like gradual failure factors, interrupters, electrical lines, cables, adapters or receptacle, other power equipments and mechanisms, etc. raises its temperature due to the increasing of the frictional resistance, so their deteriorating phenomena become repetitive.
Herein, it is noted that the temperature coefficient is a rate of increasing or decreasing an inherent resistance of an electrical appliance equipment and mechanism according to the raising or lowering of a temperature. The more the temperature coefficient is increased, the more the inherent resistance is. At that time, a current flowing into the interrupter of the electrical appliance equipment and mechanism is reduced enough to be not initiated in itself, and on the contrary, a leakage current is increased, so it may be a cause that accidental fire or accident may happen resulting from causalities or losses of tangible and intangible properties.
In order to resolve these and those problems, one object of the invention is to provide an automatic trip device, a network system using it and control method thereof to check a temperature of a power line using a temperature sensor, calculate its resistance temperature coefficient and change the maximum allowance current according to the resistance temperature coefficient, so that if a current over a setting current is detected, they are automatically tripped in an independent or a group.
Another object of the invention is to provide an automatic trip device, a network system using it and control method thereof to automatically change a setting current value that is a maximum allowance current by the reference of a data calculated from a temperature coefficient.
Another object of the invention is to provide an automatic trip device, a network system using it and control method thereof to measure a temperature of a power line and a current used, judge whether it is abnormal, give a warning and interrupt the power supply, thereby preventing the overheating of the power line.
Another object of the invention is to provide an automatic trip device, a network system using it and control method thereof to grasp the power use state of a district provided with electrical appliance equipments and mechanisms at a glance and predict a potential accident occurrence, thereby preventing the accident of causalities, fires, property losses, etc.